Rhizobia dispersion by Trichoderma harzianum hyphae

ITURRALDE, ESTEBAN TOMÁS; COLLA, DELFINA; LUCHETTI, ABRIL; TORRES TEJERIZO, GONZALO A.; PÉREZ GIMÉNEZ, JULIETA

Congreso; Unity in Diversity - ISME Virtual Microbial Ecology Summit; 2020

Soybean crops are inoculated with Bradyrhizobium spp. Competition for nodulation is aproblem faced by the rhizobia of the inoculant. One way to solve the problem is to improve thedistribution of rhizobia in the soil, but we know that motility of bacteria is limited when soils areat field capacity. On the other hand, fungal hyphae are able to colonize soils and grow in poresthat have air. It has been shown that the mycelia can be used as pathways for the active dispersalof bacteria (fungal highway). In this way, mycelial networks could play an important roledispersing the bacteria in soils at field capacity.Previously, we demonstrated the efficiency of coinoculation between Bradyrhizobiumspp. and Trichoderma harzianum, in order to improve the distribution of rhizobia. We generatedan in vitro system to test the fungal highway mechanism in a divided Petri dish. On one side, B.diazoefficiens USDA 110 GFP and T. harzianum were inoculated, and on the other side, agerminated seed was placed. When hyphae had reached the soybean roots the germinatedseeds were planted in pots. After 21 days post inoculation, the nodules were infected and thiswas observed by microscopy. The bacteria could be dispersed by fungus hyphae. This could allowrhizobia to colonize other niches and thus benefit competition for nodulation. Adding T.harzianum to Bradyrhizobium spp. inoculants could improve the distribution of bacteria in soilby fungal highway.